This application is based on Application No. 2001-155809, filed in Japan on May 24, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a vehicle surroundings monitoring device that is mounted on a vehicle and monitors the surroundings of a vehicle, and more particularly to a vehicle surroundings monitoring device that calls an alarm to a driver in order to prevent a contact and collision with an obstacle at the time of changing a lane or the like.
2. Description of the Related Art
A conventional vehicle surroundings monitoring device has been disclosed in, for example, Japanese Patent Application Laid-open No. Sho 54-45040. This vehicle surroundings monitoring device has a reflector in a mirror case so as to reflect electric waves radiated from a feeder phone antenna outside of a mirror toward the rear side of the vehicle. Also, the present applicant has disclosed a vehicle surroundings monitoring device mounted in the interior of the door mirror of the vehicle in Japanese Patent Application No. Hei 11-325688. This vehicle surroundings monitoring device includes: a transmitting circuit that generates waves to be transmitted; an antenna that radiates the transmitted waves through a mirror surface of the door mirror; and a receiving circuit that receives reflected waves from an object existing near the vehicle through the surface of the door mirror by the antenna, in which the wavelengths of a visible light is reflected onto the surface of the door mirror, and a reflective film through which electromagnetic waves of several G to 100 GHz can be transmitted is vapor-deposited on the surface of the door mirror.
However, in the case where the antenna disposed in the vicinity or the interior of the door mirror is fixed independently to the mirror case or a support portion for the door mirror surface as in the above-described conventional vehicle surroundings monitoring device, not only an additional mounting space is required to mount the antenna is excessively occupied, but also an angle of the antenna cannot be readily changed. Also, there is the possibility that the door mirror is damaged due to a contact of the antenna with the door mirror when the door mirror is rotated.
Also, similarly, even in the case where the reflective film through which the electromagnetic waves can be transmitted is vapor-deposited on the surface of the door mirror as described above, a reflection from a mirror base surface and a reflection due to the reflective film also occur to same degree. For that reason, the electric waves radiated from the transmitting antenna stray into the receiving antenna. The level of straying of the reflected waves greatly varies according to the relative positions of the mirror base material, the reflective film, and the antenna. In the case where the straying level of the reflected waves has changed significantly, when an obstacle actually exists at a short distance from the vehicle, the obstacle cannot be detected depending on the distance resolution of a radar, or the distance measuring performance is adversely affected by the fluctuation, whereby the possibility of an alarm failure or a false alarm becomes high.
The present invention has been made in order to solve the above problems, and therefore an object of the present invention is to provide a vehicle surroundings monitoring device which is capable of varying an angle of an antenna equipped within a door mirror, to thereby prevent a door mirror surface from being damaged due to a contact of the antenna with the door mirror.
Another object of the present invention is to provide a vehicle surroundings monitoring device which is capable of being downsized and improving the mounting property of the antenna in the door mirror.
Still another object of the present invention is to provide a vehicle surroundings monitoring device which is capable of reducing electric wave components that stray into a receiving antenna from a transmitting antenna to a predetermined level, to thereby prevent the distance measuring performance over a short distance from being deteriorated.
To achieve the above-described objects, according to one aspect of the present invention, there is provided a vehicle surroundings monitoring device which monitors surroundings of a vehicle, the device comprises: a transmitting antenna which is mounted in the interior of a door mirror of the vehicle and radiates transmitted waves through the surface of the door mirror; and a receiving antenna that receives reflective waves from an object existing near the vehicle through the surface of the door mirror, wherein the transmitting antenna and the receiving antenna are rotated by a drive portion equipped within the door mirror.
Also, the transmitting antenna and the receiving antenna are fixed to a support portion that supports the surface of the door mirror; and the support portion is joined to the drive portion by a joint portion and rotates vertically and horizontally with the joint portion as a fulcrum, to thereby vertically and horizontally rotate the transmitting antenna and the receiving antenna with the joint portion as the fulcrum.
Further the support portion of the door mirror surface, the transmitting antenna and the receiving antenna are molded integrally.
Furthermore, according to another aspect of the present invention, there is provided a vehicle surroundings monitoring device which monitors surroundings of a vehicle, the device comprises: a transmitting antenna which is mounted in the interior of a door mirror of a vehicle and radiates transmitted waves through the surface of the door mirror; and a receiving antenna that receives reflective waves from an object existing near the vehicle through the surface of the door mirror, wherein the support portion of the door mirror surface, the transmitting antenna and the receiving antenna are molded integrally.
Still further, the transmitting antenna and the receiving antenna are disposed at positions where the reflection from the door mirror surface becomes minimum.
Finally, a distance d of from the opening surfaces of the transmitting antenna and the receiving antenna to the door mirror surface is set to xcex/2 (xcex is a wavelength) or more.